Early fire helmets were designed without goggles or face shields. These helmets provided no protection for the eyes or face from the hazardous environments that fire fighters face. However, modern fire helmets incorporate the use of a face shield, and the inclusion of a shield was mandated by the National Fire Protection Association, NFPA, 1972. These face shields are generally sheets of material which extend curvingly about the front portion of a helmet. The shields are usually curved about a vertical axis, and are attached to the helmet at their upper corners which are almost parallel to each other due to the shield's curvature. They are usually pivotable with respect to the helmet and can be raised and lowered much like the visor on a suit of armor is raised and lowered.
These face shields unfortunately have many design flaws, including lack of protection for eyes from objects or particles that come from an upward deflection under the lower edge of the shield or from a side upward deflection around the outer vertical edge of the shield. The shields also have a high tendency to fog due to the distance of the shield from the face, and in conjunction with the seal at the top with the helmet which reduces upward ventilation of both exhaled air and evaporation of sweat from the face.
Face shields are stored while still attached to the top of the helmet. This mounting, together with their large size, causes face shields to receive damage, such as scratches and abrasions, rendering face shields virtually useless to see through over even a short period of time. When in service, the shields come into contact with smoke residue and heat. These conditions cause the shields to degrade even more rapidly as the scratches trap the smoke residue and bake it into the exposed pores of the shield.
The shields, which are typically made of plastic, are extremely difficult to clean. Many solvents which would be effective in removing the smoke residue would also cause dissolution of the plastic. Further, as time elapses, the collection of scratches and smoke residue seriously impair the fire fighter's ability to see. The shields typically lie a few inches in front of the fire fighter's eyes. It is much more difficult to discount distortions in the visual field when they occur this far from the eyes. There is a tendency to continually confuse obstructions on the shield with objects in the visual plane.
Such confusion from distortions on the shield occurs not only over time, but can occur with a new shield upon its first use. This is due to the conditions under which fires are battled, in which a shield may become obstructed with smoke residue and dirt and water even if it is in an otherwise unscratched state. In the heat of the moment when fighting a fire, the fire fighter's only quick recourse to a dirty shield is to rub away the dirt and debris with the hands or gloves. Due to the size of the shield, this will result in streaks and larger distortions. Further attempts to remove these streaks and larger distortions will only cost the fire fighter more time, time being a premium commodity during the fighting of a fire.
Further, due to the shield's distance from both the eyes and face, smoke residue, dirt and water can collect on the shield from the inside as well as the outside to compound the obstruction of the fire fighter's vision. Attempts to quickly, with the hands or gloves, wipe clean a surface having two obstructed sides are nearly impossible. Further, the face shields allow smoke to come into direct contact with the fire fighter's eyes.
Face shields also increase the overall weight of the helmet by more than fourteen ounces, and add mass forward of the helmet resulting in a forward, downward bending moment causing increased neck strain and fatigue on the wearer of the helmet. Face shield mounting hardware has a tendency to loosen with use and make the shield hang halfway down, obstructing sight with the bottom edge of the shield most prominent in the field of view.
Some of the shields currently in use are, for example, the S-601 Polycarbonate lens, the Hi-Pivot, S-901 Tuffshield, and the S-10 Bourke safety eye shield, all made by Cairns and Brothers. Others include the catalog No. 50110 four inch polycarbonate face shield and the No.50112 polycarbonate face shield manufactured by Cascade Fire Equipment Co. These designations may be trademarks of their respective manufacturers.
The use of goggles can assist in the elimination of some of the shortcomings of the shield. Goggles are currently available in several forms from the manufacturers. They may be purchased with a standard width 1/2 inch wide rubber band which may be pre-adjusted before wear or before storage. Some of the goggle straps available include neoprene rubber and several are made by Cascade Fire Equipment Co. The pre-adjustment causes the band to either be adjusted to fit the helmet in the storage position, or to fit the wearer without the helmet. Adjustment can be a significant problem, especially with rubber or elastic since the loose end must be "picked" out of the strap keeper in order to make the adjustment. Unfortunately, the goggles cannot be adjusted on the helmet and later worn on the face without hanging loosely on the face. The narrow strap also becomes uncomfortable if worn for too long of a period of time.
General problems with ordinary rubber strapping includes its lack of quick adjustability from face to helmet, easy breakage of the thin rubber, the susceptibility of the rubber to melting, and the fact that it is not securable to the helmet.
Goggle manufacturers commonly supply consumers with ordinary, somewhat shorter straps for wearing the goggles directly, without a helmet. Such straps can sometimes be used to hold goggles to helmets. Originally, these straps were designed to fit the head of the wearer without a helmet. They were not designed to function both on the helmet and later on the face. Previous goggle retainers are unable to adequately function for that purpose.
Later, other types of retainers were created for helmet use. One company known both as "Mine Safety" and "M.S.A." has manufactured a hard plastic band that mounts to the rear edge of the helmet and secures with a rubber tube around the front of the helmet. This plastic tube then contains an elastic string which secures to the goggles. This system is effective for helmets with a brim, but the elastic string tends to experience stretch failure rather rapidly, and becomes loose while in the donned position, requiring constant re-tying until no elasticity remains in the string. Other problems include the inability of the "Mine Safety" system to fit over new NFPA required edge protection, the fact that all of the components used in this system can melt or be damaged by heat, and that the system is designed to be used only with helmets.
Another goggle maker has a retainer consisting of a buckle to adjust the goggles. This buckle is mountable to only their brand goggle, and works only with the 1/2 inch rubber band. This buckle is specifically designed for that use. It is difficult to use with gloves and can be difficult to doff.
What is therefore needed is a system for the protection of fire fighter's eyes from heat, smoke and debris, which is easily managed and can be wiped adequately clean in a moment if obstructed. It should be amenable to being worn either with or without a helmet, and should be adjustable by the wearer rapidly and when in place on either a helmet or the wearer's head. The system should employ support structures which will always work. If the design contains elastic, it should work even if the elastic wears out. The system should be easy to use with gloved hands, and during fire fighting operations.